66 C-10 LWB, RPO code for axle ratio? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

littlevictories · 01-01-2014, 10:47 PM

Hey folks,

I've always assumed this truck had 4:11 gears stock, but with a bit more research I'm not so sure.

the RPO code for the axle on the glovebox door reads something like:

G80AA positrack axle R

It's cold outside but I guess I got some laying under the truck to do.

Any help would be appreciated.

**rideblue00** · 01-02-2014, 07:38 AM

Look on the top of the righthand axle tube, right next to the center section. Should be a 3 digit code stamped on there. Take a wire brush with you. But to know for sure of course, taking the cover off the back will be the only way.

**aerotruk63** · 01-02-2014, 12:40 PM

G80 is the Positraction RPO code.

**Captainfab** · 01-03-2014, 01:32 AM

Once you find the code on the passenger side axle tube, you can look it up here in post #6.......

http://www.67-72chevytrucks.com/vboa...d.php?t=327764

However I always suggest as rideblueOO said, just pull the rear cover and have a look. You can either count the teeth or find the tooth count stamped on the edge of the ring gear. Who knows what has been done to the differential in the past 47 years. The differential is one of the most neglected parts of a vehicle. Yours could most likely use an oil change. All it'll cost you is a couple quarts of gear oil and a cover gasket, and a little time. Then you'll know for sure what gears you have and have the satisfaction of knowing your diff has fresh and clean oil in it.

littlevictories · 01-03-2014, 12:05 PM

yep that looks like what I oughta do. I know my pop changed the gear oil several years ago, but it's probably about time.

i messed with it last night. only stamping i found was on the driver side axle tube "68" from what I could see.

should the stamp be inboard or outboard of the brake line tab?

also did the one wheel off the ground, turn it twice and count the driveline revs method.
came up with 3.73's

recommend a gear lube and posi additive that these trucks like?

oem4me · 01-03-2014, 12:08 PM

On the off chance you found a build sheet, the axle ratio code would be on it.

littlevictories · 01-03-2014, 12:20 PM

the build sheet is in the seat, but it's in really rough shape
i can see a couple boxes with two-letter codes but can't read the name of the boxes
suppose i oughta dig it out carefully before it gets worse

oem4me · 01-03-2014, 12:33 PM

Quote:

Originally Posted by littlevictories

the build sheet is in the seat, but it's in really rough shape
i can see a couple boxes with two-letter codes but can't read the name of the boxes
suppose i oughta dig it out carefully before it gets worse

Near the top center. Box 18. Mine says HA for 3.73. See pic.

littlevictories · 01-04-2014, 11:09 AM

thanks!
it came out in pieces, but i could read the code as HC, 3.73 posi
which matches what it rolls out as

01-01-2014, 10:47 PM	#1
littlevictories Registered User Join Date: Dec 2013 Location: Portland, Ore. Posts: 348	66 C-10 LWB, RPO code for axle ratio? Hey folks, I've always assumed this truck had 4:11 gears stock, but with a bit more research I'm not so sure. the RPO code for the axle on the glovebox door reads something like: G80AA positrack axle R It's cold outside but I guess I got some laying under the truck to do. Any help would be appreciated.

01-02-2014, 07:38 AM	#2
rideblue00 Senior Member Join Date: Feb 2010 Location: Lambertville, MI Posts: 1,865	Re: 66 C-10 LWB, RPO code for axle ratio? Look on the top of the righthand axle tube, right next to the center section. Should be a 3 digit code stamped on there. Take a wire brush with you. But to know for sure of course, taking the cover off the back will be the only way.

01-02-2014, 12:40 PM	#3
aerotruk63 Check The Champ, Demonstrator Join Date: Jun 2009 Location: Montreal,Quebec Posts: 6,627	Re: 66 C-10 LWB, RPO code for axle ratio? G80 is the Positraction RPO code. __________________ 1963 *Chevrolet Truck* Literature LINK: https://picasaweb.google.com/113840717762774560215 YouTube Channel with 20+ Original *Chevrolet Truck* Salesmen, Mechanics & Service Department Training Slideshows. https://www.youtube.com/results?sear...otruk63&page=1 Last edited by aerotruk63; 01-02-2014 at 05:25 PM.

01-03-2014, 01:32 AM	#4
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,252	Re: 66 C-10 LWB, RPO code for axle ratio? Once you find the code on the passenger side axle tube, you can look it up here in post #6....... http://www.67-72chevytrucks.com/vboa...d.php?t=327764 However I always suggest as rideblueOO said, just pull the rear cover and have a look. You can either count the teeth or find the tooth count stamped on the edge of the ring gear. Who knows what has been done to the differential in the past 47 years. The differential is one of the most neglected parts of a vehicle. Yours could most likely use an oil change. All it'll cost you is a couple quarts of gear oil and a cover gasket, and a little time. Then you'll know for sure what gears you have and have the satisfaction of knowing your diff has fresh and clean oil in it. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

01-03-2014, 12:05 PM	#5
littlevictories Registered User Join Date: Dec 2013 Location: Portland, Ore. Posts: 348	Re: 66 C-10 LWB, RPO code for axle ratio? yep that looks like what I oughta do. I know my pop changed the gear oil several years ago, but it's probably about time. i messed with it last night. only stamping i found was on the driver side axle tube "68" from what I could see. should the stamp be inboard or outboard of the brake line tab? also did the one wheel off the ground, turn it twice and count the driveline revs method. came up with 3.73's recommend a gear lube and posi additive that these trucks like?

01-03-2014, 12:08 PM	#6
oem4me Registered User Join Date: Aug 2010 Location: Burbank CA Posts: 3,055	Re: 66 C-10 LWB, RPO code for axle ratio? On the off chance you found a build sheet, the axle ratio code would be on it.

01-03-2014, 12:20 PM	#7
littlevictories Registered User Join Date: Dec 2013 Location: Portland, Ore. Posts: 348	Re: 66 C-10 LWB, RPO code for axle ratio? the build sheet is in the seat, but it's in really rough shape i can see a couple boxes with two-letter codes but can't read the name of the boxes suppose i oughta dig it out carefully before it gets worse

01-04-2014, 11:09 AM	#9
littlevictories Registered User Join Date: Dec 2013 Location: Portland, Ore. Posts: 348	Re: 66 C-10 LWB, RPO code for axle ratio? thanks! it came out in pieces, but i could read the code as HC, 3.73 posi which matches what it rolls out as



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